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PRISM Manual | ThePRISMLanguage / Example2 
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    <p><a class='wikilink' href='Introduction.html'>The PRISM Language</a> /
</p><h1>Example 2</h1>

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<p>We now introduce a second example: a CTMC that models an <em>N</em>-place queue of jobs and
a server which removes jobs from the queue and processes them.
The PRISM code is as follows:
</p>
<div class='vspace'></div>
<div class='sourceblock ' id='sourceblock1'>
  <div class='sourceblocktext'><div class="prism"><span class="prismcomment">// Example 2</span><br/>
<span class="prismcomment">// N-place queue + server</span><br/>
<br/>
<span class="prismkeyword">ctmc</span><br/>
<br/>
<span class="prismkeyword">const</span> <span class="prismkeyword">int</span> <span class="prismident">N</span> = <span class="prismnum">10</span>;<br/>
<span class="prismkeyword">const</span> <span class="prismkeyword">double</span> <span class="prismident">mu</span> = <span class="prismnum">1</span>/<span class="prismnum">10</span>;<br/>
<span class="prismkeyword">const</span> <span class="prismkeyword">double</span> <span class="prismident">lambda</span> = <span class="prismnum">1</span>/<span class="prismnum">2</span>;<br/>
<span class="prismkeyword">const</span> <span class="prismkeyword">double</span> <span class="prismident">gamma</span> = <span class="prismnum">1</span>/<span class="prismnum">3</span>;<br/>
<br/>
<span class="prismkeyword">module</span> <span class="prismident">queue</span><br/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="prismident">q</span> : [<span class="prismnum">0</span>..<span class="prismident">N</span>];<br/>
<br/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[] <span class="prismident">q</span>&lt;<span class="prismident">N</span> -&gt; <span class="prismident">mu</span>:(<span class="prismident">q</span>'=<span class="prismident">q</span>+<span class="prismnum">1</span>);<br/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[] <span class="prismident">q</span>=<span class="prismident">N</span> -&gt; <span class="prismident">mu</span>:(<span class="prismident">q</span>'=<span class="prismident">q</span>);<br/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[<span class="prismident">serve</span>] <span class="prismident">q</span>&gt;<span class="prismnum">0</span> -&gt; <span class="prismident">lambda</span>:(<span class="prismident">q</span>'=<span class="prismident">q</span>-<span class="prismnum">1</span>);<br/>
<span class="prismkeyword">endmodule</span><br/>
<br/>
<span class="prismkeyword">module</span> <span class="prismident">server</span><br/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="prismident">s</span> : [<span class="prismnum">0</span>..<span class="prismnum">1</span>];<br/>
<br/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[<span class="prismident">serve</span>] <span class="prismident">s</span>=<span class="prismnum">0</span> -&gt; <span class="prismnum">1</span>:(<span class="prismident">s</span>'=<span class="prismnum">1</span>);<br/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[] <span class="prismident">s</span>=<span class="prismnum">1</span> -&gt; <span class="prismident">gamma</span>:(<span class="prismident">s</span>'=<span class="prismnum">0</span>);<br/>
<span class="prismkeyword">endmodule</span><br/>
</div></div>
  <div class='sourceblocklink'><a href='Example2@action=sourceblock&amp;num=1' type='text/plain'>[&#036;[Get Code]]</a></div>
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<p class='vspace'  style='text-align: center;'><strong>The PRISM Language: Example 2</strong>
</p>
<p class='vspace'>This example also introduces a number of other PRISM language concepts,
including <a class='wikilink' href='Constants.html'>constants</a>, action labels and <a class='wikilink' href='Synchronisation.html'>synchronisation</a>.
These are described in the following sections.
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<h3><a class='wikilink' href='../Main/Welcome.html'>PRISM Manual</a></h3>
<p><strong><a class='wikilink' href='Introduction.html'>The PRISM Language</a></strong>
</p><ul><li><a class='wikilink' href='Introduction.html'>Introduction</a>
</li><li><a class='wikilink' href='Example1.html'>Example 1</a>
</li><li><a class='wikilink' href='ModelType.html'>Model Type</a>
</li><li><a class='wikilink' href='ModulesAndVariables.html'>Modules And Variables</a>
</li><li><a class='wikilink' href='Commands.html'>Commands</a>
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</li><li><a class='wikilink' href='CTMCs.html'>CTMCs</a>
</li><li><a class='selflink' href='Example2.html'>Example 2</a>
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